Everyday Cryptography: Fundamental Principles and Applications Keith M. Martin

Part I
Setting the Scene

1
Basic Principles
This chapter serves as an introduction to the environment in which cryptography finds common use
today. We discuss the need for cryptography, as well as the basic language and concepts that are used
to describe a cryptographic system.
At the end of this chapter, you should be able to:
• Justify the need for information security.
• Identify some of the essential security requirements of the modern world.
• Appreciate the most significant risks to which information is exposed.
• Identify a number of different security services that cryptography can provide.
• Describe the basic model of a cryptosystem.
• Recognise the differences between symmetric and public-key (asymmetric) cryptosystems.
• Appreciate the importance of identifying the assumptions about what an attacker knows about a cryptosystem.
• Discuss what it means to break a cryptosystem.

Everyday Cryptography: Fundamental Principles and Applications Keith M. Martin